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Rototillers Of The Rockies

A grizzly bear, Ursus arctos. (MAIA C, flickr)

Today's Moment of Science "digs up" the story behind one of the grizzly bear's more unusual nicknames: the "Rototiller of the Rockies."

Grizzly Bear Claws

Grizzly bear claws are huge, usually three to four inches long. This is perfect for an animal who survives by digging around in the landscape, unearthing tasty treats like ground squirrels and root vegetables.

One of the grizzly bear's favorite early season foods is the glacier lily, a beautiful yellow flower with a starchy, nutritious bulb. Bears "till" up the land, turning over chunks of soil to access those tasty bulbs. And guess what: scientists working in Glacier Park, Montana have learned that this "tilling" has some important side effects. Areas with recent bear diggings have less plant diversity and higher nitrogen levels than undisturbed parts of the landscape.

Without much competition from other plants, left behind glacier lily bulbs can quickly regenerate, and these new lilies produce twice the usual number of seeds, thanks to the nitrogen rich soil!

Digging Up Delicious Treats

We humans have also gained important culinary knowledge. You see, after digging up glacier lilies, bears often leave the bulbs for a few days to wilt in the sun.

This "cooks" them a bit, and makes them sweeter and easier to digest. First Nations lore shows that early peoples learned to dry and cook glacier lily bulbs by copying the grizzly bear.

Sources And Further Reading:

Doak, Daniel F. and Michael G. Loso. "Effect of Grizzly Bear Digging on Alpine Plant Community Structure." Arctic, Antactic and Alpine Research. 35:4 (2003), 421 8.

Tardiff, Sandra E. and Jack A. Stanford. "Grizzly Bear Digging: Effects on Subalpine Meadow Plants in relation to Mineral Nitrogen Availability." Ecology. 9:7 (1998), 2219 29.

Turner, Nancy J., Marianne Boelscher Ignace and Ronald Ignace. "Traditional Ecological Knowledge and Wisdom of Aboriginal Peoples in British Columbia." Ecological Applications. 10:5 (2000), 1275 87.

"Yellow Glacier Lily." "Notable Wildflowers of Yellowstone." Yellowstone National Park Lodges. http://www.yellowstonenationalparklodges.com/Notable Native Wildflowers of Yellowstone 5653.html.

"Yellow Glacier Lily." Plant Life.org. http://montana.plant life.org/species/erythro_gran.htm

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